Comparison of the seroconversion rate after primary hepatitis B vaccination and after revaccination of non-responders in full-term infants according to mother's HBsAg seropositivity / 소아과

PURPOSE: This study aimed to identify the true extent of non-responsiveness in full-term infants born from HBsAg-negative or HBsAg-positive mothers and vaccinated against hepatitis B virus (HBV) at 0, 1, and 6 months of age and to evaluate the effect of revaccination among non-responders. METHODS: The study included 716 full-term infants born in 2004-2007. Of 716, 662 infants (A group) were born to HBsAg- negative mothers and 54 infants (B group: 50, except HBsAg-positive infants) were born to HBsAg-positive mothers. All infants were administered DNA recombinant vaccines at 0, 1, and 6 months of age. B group infants received hepatitis B immunoglobulin at birth. Anti-HBs titers were tested at 7-12 and 9-15 months in A and B groups, respectively. Three revaccination doses were administered to non-responders whose anti-HBs titers were under 10 mIU/ml; revaccinated infants were retested at 1-3 months after last vaccination. The association between HBeAg seropositivity of mother and the failure of HBV immunoprophylaxis was evaluated. RESULTS: The seroconversion rates after primary hepatitis B vaccination were higher in A group (94.1%) than in B group (78%, P<0.001). The seroconversion rates were high in revaccinated infants (A group non-responders: 96.9%, B group non- responders: 87.5%). The failure of HBV immunoprophylaxis was significantly associated with maternal HBeAg seropositivity (P<0.001). CONCLUSION: The seroconversion rates after primary hepatitis B vaccination were low in B group infants. Revaccination of non-responders in B group was very effective. Therefore, anti-HBs testing and revaccination of B group is very important. Revaccination of non-responders in A group was also very effective. Thus, testing the immune status of infants born to HBsAg-negative mothers even after primary hepatitis B vaccination should be considered. However, to realize this, further studies on the cost-effectiveness of anti-HBs testing in healthy full-term infants are necessary.

Incidence of hearing loss and importance of risk factors in the neonatal intensive care unit / 소아과

PURPOSE: To assess the incidence of neonatal hearing loss in a neonatal intensive care unit and the relative importance of risk factors for hearing imparement in a neonatal intensive care unit which the Joint Committee on Infant Hearing(JCIH) had recommended. METHODS: One thousand, two hundred and one newborns admitted to the Good Moonhwa Intensive Care Unit from May 2003 to December 2005 were assesed using the automated auditory brainstem response(AABR). The screening was performed on those aged more than 36 weeks and weighing more than 2,200 g. We divided the infants into two groups, 'pass' and 'refer'. The 'refer' group were retested one month later, and if classified as 'refer' during the retest, were referred to a hearing impairment clinic. RESULTS: From the 1,201 neonates, 1,187(98.8 percent) passed the test and 14(1.2 percent) failed. 293(24.4 percent) of the 1,201 neonates had a risk factor for hearing impairment; 282(96.2 percent) passed the test and 11(3.8 percent) failed. The group with risk factors were shown to have a higher incidence of hearing loss(P<0.001). The neonates in the refer group were shown to have a higher incidence of ototoxic drugs(P<0.001), low birth weight(<1,500 g)(P<0.001) and craniofacial anomalies(P=0.007). On the other hand, there were no statistical differences between the pass and refer groups in congenital infection, hyperbilirubinemia, bacterial meningitis, low Apgar scores, prolonged mechanical ventilation and syndromes known to include hearing loss. CONCLUSION: In order to identify hearing-impaired infants within an appropriate period, neonatal hearing screening tests and identification of the risk factors for neonatal hearing loss are important.

Investigation of Automated Neonatal Hearing Screening for Early Detection of Childhood Hearing Impairment / 소아과

PURPOSE: Early diagnosis of congenital hearing loss through the neonatal hearing screening test minimizes language defect. This research intends to identify frequency of congenital hearing loss in infants through neonatal hearing screening test with the aim of communicating the importance of hearing test for infants. METHODS: From May 20, 2003 to May 19, 2004, infants were subjected to Automated Auditory Brainstem Response test during one month of birth to conduct the test with 35 dB sound. Infants who passed the 1st round of hearing test, were classified into 'pass' group whereas those who did not were classified into 'refer' group. Infants who did not 'pass' in the hearing test conducted within one month of birth were subjected to re-test one month later, and if classified as 'refer' during the re-test, they were subjected to the diagnosis for validation of hearing loss by requesting test to the hearing loss clinic. RESULTS: There was no difference among the 'pass' and 'refer' group in terms of form of childbirth, weight at birth and gestational age. In the 1st test, total of 45 infants were classified into 'refer' group. Six among 35 who were subjected to re-test (17%) did not pass the re-test, and all were diagnosed with congenital hearing loss. This corresponds to 0.35% (3.5 per 1, 000) among total number of 1, 718 subjects. CONCLUSION: In our study the congenital hearing loss tends to be considerably more frequently than congenital metabolic disorder. Accordingly, newly born infants are strongly recommended to undergo neonatal hearing screening test.